This project will develop a practical method for isolating granulocytes and platelets from whole blood. The cell suspensions will be tagged with lipophilic chelating agents such as 8-hydroxyquinoline complexed with 99mTc and 111In and re-injected intravenously for localization of abscesses, other inflammatory lesions, thrombi, and infarcts by gamma scintigraphy. The efficacy of detection will be compared with that of conventional radiopharmaceuticals such as 67Ga citrate and I125 fibrinogen in dogs and rabbits with induced abscesses and thrombi before human trials. In addition, labeled platelets will be used in an attempt to identify early human transplant rejection at a stage prior to deterioration of transplant function as evidenced by abnormal handling of conventional renal pharmaceuticals (131I Hippuran, 99mTc-DTPA and/or 99mTc-GHA). The role of platelet accumulation as an etiologic factor in stress induced myocardial injury will also be assessed by comparing platelet accumulation within the stress-injured myocardium of rats treated with anti-platelet drugs (such as dipyridamole) to labeled platelet accumulation in the stress-injured myocardium of un-treated rats. (The levels of stress-induced myocardial injury will be quantitated in the anti-platelet-treated and non-treated animals by determination of myocardial 99mTc-pyrophosphate accumulation). Radioactive complexes of various lipophilic chelates including the prophyrines will be compared with 8-hydroxyquinoline for their ability to label isolated blood cellular componants.